Hybrid functionals with local range separation: Accurate atomization energies and reaction barrier heights

Abstract

Range-separated hybrid approximations to the exchange–correlation density functional mix exact and semi-local exchange in a position-dependent manner. In their conventional form, the range separation is controlled by a constant parameter. Turning this constant into a density functional leads to a locally space-dependent range-separation function and thus a more powerful and flexible range-separation approach. In this work, we explore the self-consistent implementation of a local range-separated hybrid, taking into account a one-electron self-interaction correction and the behavior under uniform density scaling. We discuss different forms of the local range-separation function that depend on the electron density, its gradient, and the kinetic energy density. For test sets of atomization energies, reaction barrier heights, and total energies of atoms, we demonstrate that our best model is a clear improvement over common global range-separated hybrid functionals and can compete with density functionals that contain multiple empirical parameters. Promising results for equilibrium bond lengths, harmonic vibrational frequencies, and vertical ionization potentials further underline the potential and flexibility of our approach.

Full Implementation, Optimization, and Evaluation of a Range-Separated Local Hybrid Functional with Wide Accuracy for Ground and Excited States

“…The Scuseria, Perdew, and Savin groups introduced hybrids with local range separation (LRSHs), where the normally constant range-separation parameter ω is replaced by a position-dependent range-separation function. While the first self-consistent implementation of LRSHs had to make use of a number of approximations, , recent efficient and accurate implementations based on seminumerical integration have been reported. − The second combination of RSH and LH ideas, on which the present work centers, is the local mixing of short- and long-range exchange-energy densities by an LMF. This leads to a range-separated local hybrid functional (RSLH). , Initial self-consistent implementations used a resolution of the identity (RI) to avoid the computation of nonstandard two-electron integrals and were not computationally competitive.…”

Understanding Primary Charge Separation in the Heliobacterial Reaction Center

“…We use the range-separated hybrid functional ωPBE with the range-separation parameter ω = 0.171 a 0 –1 . The basic idea behind choosing this particular value of ω is the one of optimal tuning. ,,− We explain the reasoning behind our specific choice of the range-separation parameter in detail in the Supporting Information. We use the 6-31G basis set which was demonstrated to be sufficient for obtaining reliable results in terms of the relative energetic positioning of the excitations .…”

Can range-separated functionals be optimally tuned to predict spectra and excited state dynamics in photoactive iron complexes?

“…Despite the fact that tuned range-separated functionals have been shown to be very useful for describing properties related to fundamental and optical energy gaps, [22][23][24][25][26][27][28][29][30][31][32] it can be non-trivial to obtain a unique set of range-separation parameters, 25 particularly if one needs to describe both CT and locally excited states on the same footing. Furthermore, it is far from obvious whether different parameters would ultimately lead to the same relaxation mechanisms aer light irradiation.…”